SNAFUs From The Field


Little things I have seen that made for interesting times.
Most recent at the bottom of the page.


So our Conveyance & Distribution guys were getting all new trucks a few years back. They'd be delivered to our facility and the fleet garage would ask me to install the obligatory low band two way radio system in them. No worries. Except that nobody bothered to tell me that the next stop the trucks would make was the contractor who would install the new arrow boards. The very first truck that went to this contractor came back in a couple of days, and immediately I got a call from the truck operator to tell me that his new radio in his new truck didn't work.

Really? Bending that whip over and clamping it to the rack, where it is perfectly sandwiched between two metallic slabs, shouldn't have been a tip-off?

In his defense the contractor's installer said "Hey, that clamp is insulated! Look ... it has rubber on it!"

Thanks for that. Antenna relocated to an outer corner of the arrow board rack.

(A side note that came to my attention later: some of the controllers for these arrow boards weren't well built and had little to no immunity to RF, and occasionally the boards would raise up and / or start flashing while the vehicle operators were using the radio. Seemed to make no difference whether they were at rest or in motion. Those arrow boards make a lot of noise when they deploy while at 75 MPH!)


Our headquarters building is in downtown Los Angeles, with the customary underground parking garage. Quite a few of our field supervisors leap at the opportunity to go there and test their ability to compete in the rarified and heady atmosphere of the power brokers that dwell within. Perhaps those folks are breathing the same kind of air as the arrow board contractor's installer, which allows me to offer another variation of mobile antenna mayhem -

Most of these guys have the time and / or common sense to take the antennas off their trucks before they enter the garage. A few of them are in a hurry, I guess, or aren't tall enough or dextrous enough to reach them and actually spin them off the mounts, and this is what we end up with.

That's a stacked 5/8 wave UHF antenna ...

... and that's a unity gain low band whip in the 40 MHz band.

You know this guy made a call to the shop on his cell phone later that day, or perhaps a week later, and complained that both his two-way radios were on the fritz. Amazingly, no radios were harmed in the making of this movie ...


And from the "You Can't Get There From Here" file ...

"Yes sir boss, I spent all morning driving up to the site, and had to walk the last 500 yards to the vault."


And speaking of mountain tops, some of them get a little windy at times.

A foot-deep block of concrete and some wall brackets might not be enough keep your fifty foot tower standing upright in 80 mile per hour winds.


What's Passive Intermodulation?

"It's worse than that, Jim. He's dead."

A well-meaning installer, a little pressed for time, got a little over-zealous with this Heliax connector. We couldn't understand why the repeater we had tested on the bench just that morning had failed completely both transmit and receive at the site ... that is until we got out the spectrum analyzer and return loss bridge and swept the antenna system. This one was inside the vault at the duplexer tee. After replacing it we still couldn't get better than -10dBRL, so up the tower went our guy, and the whole run of brand new LDF4-50A was let down so we could inspect the upper connector. No dead shorts, but we found copper shavings galore.

Two new Positive Stop connectors later we had return loss readings of better than -35dBRL, and our dispatch repeater was on the air.


Trained, professional installers? Who needs 'em!

I kid you not, I stumbled across this in the parking lot of a Home Depot. It's not duct tape, but it's close!
I'm sure it's functional ...


As I bump into more bits of fun I'll post them here.

E-mail Paul KB6MIP

Page last updated 8 October 2012